Bearing cages for rolling-element bearings are generally comprised of two axially-spaced-apart side rings and a plurality of bridges that connect the side rings and are disposed one behind the other in a circumferential direction of the bearing cage. Each pair of adjacent bridges forms a pocket for guiding a rolling element. The bearing cage thus holds the rolling elements spaced apart relative to each other, thereby preventing direct contact between neighboring rolling elements and thus reducing friction and heat generation in the bearing. The bearing cage also ensures a uniform distribution of the rolling elements around the entire circumference of the cage or rolling-element bearing and thus enables a uniform load distribution as well as a quiet and smooth running of the bearing.
Bearing cages are heavily stressed during operation due to frictional, strain and inertial forces. In addition, chemical degradation can occur under certain circumstances due to exposure to certain additives and substances. Design and material selection are therefore of critical importance for the operational reliability of the cage as well as for the operational efficiency of the bearing.
Rolling-element bearing cages typically comprise either pressed cages or solid cages. Pressed cages for rolling-element bearings are usually manufactured from sheet steel, in some cases also from sheet brass. Solid cages for rolling-element bearings can be manufactured, e.g., from brass, steel, aluminum, polymers or phenolic resin.
Solid polymer cages, which are often manufactured using an injection molding process, are characterized by an advantageous combination of strength and elasticity. Good sliding properties of plastic on lubricated steel surfaces and the smoothness of the cage surfaces in contact with the rolling elements lead to low cage friction, a correspondingly low heat generation in the bearing and barely measurable wear. The forces from the inertia of the cage also remain small due to the relatively low material density (as compared to heavier metal cages). The excellent running properties of polymer cages even under lubricant starvation conditions permit continued operation of the bearing for some time without risk of seizure and secondary damage.
For example, polyamide 66, polyamide 45, polyetheretherketone (PEEK), phenolic resin and other polymer materials can be used as the polymers for conventional injection-molded bearing cages.
Bearing cages are known in the prior art that have a through-slot along a cutting or parting line in the circumferential direction. The respective ends of the cage or side ring that border the cutting line are formed as bridges (circumferential bridges), which have projections and openings corresponding to one another in order to fix or couple the cage ends to each other, e.g., using a snap-fit connection. Such split rolling-element bearing cages, in which a “lock” or a “latch” attached to the cage ends secures or fixes the cage ends, can be used in many ways, such as for example for the bearing of balance shafts or for the bearing of gears on shafts in motor vehicles having a manual transmission.
In known split rolling-element bearing cages, however, the projections and openings on the cage ends are usually designed such that the cage ends are not held captive or fixed in at least one of the axial, radial, and tangential directions. As a consequence, such known connecting or fixing concepts for cage ends are disadvantageous in terms of their load bearing capacity and/or strength in at least one of the aforementioned directions.